1. Field of the Invention
The present invention relates generally to a game device having a movable body, for example, a ball, which is moved along a game board, and more particularly, to a movable body rebounding mechanism for automatically rebounding the movable body after it collides with the rebounding mechanism.
2. Description of the Related Art
Movable body rebounding mechanisms in general are known in the related art. An example of such a rebounding mechanism is a bumper mechanism of a pinball game such as that disclosed in Examined Japanese Patent Publication No. SHO 56-26428. FIGS. 9 and 10 show the construction of this type of bumper mechanism. As shown in these figures, a bumper mechanism 101 includes a pair of upper and lower disk-like bumper pieces 102a and 102b projecting from a game board 103, wherein the lower bumper piece 102b has a diameter larger than that of the upper bumper piece 102a.
The upper bumper piece 102a is formed integrally with both a leg portion 108 extending vertically downwardly from a lower surface of the upper bumper piece 102a and a supporting frame 109 horizontally extending on both sides of the leg portion 108. The supporting frame 109 is rockably supported at one end thereof through a pin 110, and is biased upward near its center by a spring 111. On the end of the supporting frame 109 opposite the pin 110, a stopper 112 is provided, which stopper 112 abuts the lower surface of the game board 103 for limiting the upper position of the upper bumper piece 102a. A rack 113 is also provided on the supporting frame 109 opposite pin 110. The rack 113 is formed in a circular-arc recessed surface around the pin 110 so as to be meshed with a planetary gear 114 described later.
The lower bumper piece 102b is formed integrally with a supporting frame 115. The supporting frame 115 restricts the size of the bumper piece 102b so that the two are in close contact. The supporting frame 115 is pivotally supported at one end thereof with a shaft 117, and is biased upward near its center by a spring 118. The supporting frame 115 is also formed with an expanding slit 120 through which the leg portion 108 of the upper bumper piece 102a passes. Further, on the end of the supporting frame 115 opposite shaft 117, there is provided a stopper 119 thereby limiting the upper position of the lower bumper piece 102b. A claw portion 122 is provided on the same side of the supporting frame 115 as the stopper 119. The claw portion 122 is removably engaged with a stopper 124 formed on the side of a frictional disk 123 which will be described later.
The bumper mechanism 101 further includes a motor 125 which is usually rotated at a constant speed, the motor 125 serving as a drive source for the upper bumper piece 102a. The motor 125 is connected to a sun gear 129 through reduction gears 126 and 127, and a shaft 128. The frictional disk 123 is biased toward the sun gear 129. This biasing is done with a clutch spring 131 abutting the side of the frictional disk 123 which has stopper 124 formed thereon. Further, a planetary gear 114 is rotatably provided on the frictional disk 123. Planetary gear 114 meshes with the sun gear 129 and the rack 113 of the supporting frame 109.
A description follows of how the bumper mechanism 101 having the above construction rebounds a ball 107 which is rolled along the game board 103 and collides with bumper mechanism 101. When the ball 107 collides with the bumper mechanism 101, the ball 107 first contacts the lower bumper piece 102b (which has a larger diameter). The weight of the ball 107 immediately forces the lower bumper piece 102b downward against the biasing force of the spring 111. When the downward displacement of the lower bumper piece 102b reaches a specified value, the claw portion 122 of the lower bumper piece 102b, which was previously engaged with the stopper 124 of the frictional disk 123, is disengaged from stopper 124. This disengagement allows the frictional disk 123 to be rotated together with the sun gear 129. The rotational force is provided by the frictional force between the sun gear 129 and the frictional disk 123 resulting from the biasing force of the clutch spring 131. Along with the rotation of the frictional disk 123, the planetary gear 114 revolves in a clockwise direction (according to the vantage of the figures) and meshes with the rack 113 of supporting frame 109 of the upper bumper piece 102a. Accordingly, the supporting frame 109 is rotated counterclockwise (according to the vantage of the figures) around the pin 110. As a result, the upper bumper piece 102a is drawn down to clamp the ball 107 in contact therewith. The ball 107 is clamped between the upper and lower bumper pieces 102a and 102b. Because of the slanted surfaces of the bumper pieces, the ball 107 is rebounded from the bumper mechanism 101.
After rebounding the ball 107, the lower bumper piece 102b is returned to its original position by the spring 118. When the frictional disk 123 rotates further and the meshing between the rack 113 of the supporting frame 109 and the planetary gear 114 is released, the upper bumper piece 102a is returned to the original position by the spring 111. With further rotation of the frictional disk 123, stopper 124 engages with the claw portion 122 of the lower bumper piece 102b against which the stopper 124 is already in the stand-by condition. This returns the mechanism to its original stage. With the above operation, the bumper mechanism 101 can repeatedly rebound the ball 107 which collides therewith.
However, as is evident from the above description, the related art bumper mechanism has a large number of parts and has a very complicated construction, for example, it requires a planetary gear. In general, a game device usually has a plurality of bumper mechanisms having the above construction. Accordingly, the bumper mechanism increases the production cost, enlarges the size of the game device, and requires complex maintenance. For these reasons, the number and the placement of the bumper mechanisms are restricted. These disadvantages are particularly inconvenient for game devices which are simple and small (e.g., table-top sized) in terms of the manufacturing expense and space allocation.